1. Field of the Invention
Embodiments of the invention generally relate to tubular connections.
2. Description of the Related Art
In order to access hydrocarbons in subsurface formations, it is typically necessary to drill a bore into the earth. The process of drilling a borehole and of subsequently completing the borehole in order to form a wellbore requires the use of various tubular strings. These tubular members are typically run downhole where the mechanical and seal integrity of the jointed connections are critically important in the original make-up of the tubular members, during expansion of the tubular members, and after expansion of the tubular members.
Typically, simple male to female threaded connections connect multiple tubular members end-to-end. The male end is generally referred to as a pin, and the female end as a box. The tubular members are connected, or “made-up,” by transmitting torque against one of the tubular members while the other tubular member is typically held stationary. Transmitting torque in a single direction corresponding with connection make-up tightens the threaded joint in order to establish the seal integrity and lock in the applied torque.
When running tubular members, there is sometimes a requirement to run jointed tubular members that will later be expanded by various types of expansion mechanisms. The most basic type of expander tool employs a simple cone-shaped body, which is typically run into a wellbore to the tubular member that is to be expanded. The expander tool is then forced through the tubular members to be expanded by pushing or pulling on the working string from the surface and/or applying fluid pressure on one side of the cone. Alternatively, rotary expander tools can employ one or more rows of compliant rollers that are urged outwardly from a body of the expander tool in order to engage and to expand the surrounding tubular member. The rotary expander tool is rotated downhole so that the actuated rollers can act against the inner surface of the tubular member to be expanded in order to expand the tubular body circumferentially. Radial expander tools are described in U.S. Pat. No. 6,457,532, issued to Simpson et al., and that patent is incorporated herein by reference in its entirety.
Expanding tubular members that use the same threaded connections as employed with conventional oil-field tubular members proves to be problematic. First, changes in geometry of the connection once expanded can reduce the locked in torque and the tensile capacity of the connection due to loss of intimate contact between the threads when the locked in torque is reduced. Additionally, a threaded connection potentially turns and loosens during expansion due to rotation and frictional contact of a rotary expansion tool. For example, left hand threaded box by pin connections rotate in the clockwise direction when expanded with the rotary expansion tool in the clockwise direction. This transferred rotation potentially slackens off the threaded connections within a multiple joint tubular string being expanded that is differentially stuck at the bottom when expansion takes place top down. On the other hand, transferred clockwise rotation from the rotary expansion tool potentially loosens the threaded connection regardless of differential sticking when expansion occurs in a bottom to top direction. Addition of right hand threaded connections for use in the tubular string to help remedy these problems related to undoing of the connection during expansion only present further issues such as inventory concerns and specialized equipment requirements.
Therefore, a need exists for an improved tubular connection that is capable of being made-up and broken-out numerous times prior to expansion while torsionally locking itself upon being expanded.